15231121221 has 32 divisors (see below), whose sum is σ = 22188974080. Its totient is φ = 9257716800.

The previous prime is 15231121207. The next prime is 15231121271. The reversal of 15231121221 is 12212113251.

It is not a de Polignac number, because 15231121221 - 2²² = 15226926917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15231121271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 296016 + ... + 343638.

It is an arithmetic number, because the mean of its divisors is an integer number (693405440).

Almost surely, 2^15231121221 is an apocalyptic number.

It is an amenable number.

15231121221 is a deficient number, since it is larger than the sum of its proper divisors (6957852859).

15231121221 is a wasteful number, since it uses less digits than its factorization.

15231121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47857.

The product of its digits is 240, while the sum is 21.

Adding to 15231121221 its reverse (12212113251), we get a palindrome (27443234472).

The spelling of 15231121221 in words is "fifteen billion, two hundred thirty-one million, one hundred twenty-one thousand, two hundred twenty-one".